In printing machines, especially in electrophotographic printing machines, printing media such as paper, for example, are conveyed along a path of travel with the aid of conveyor belts, traction systems, or the like.
Printing media can be conveyed such that only certain areas of the printing media come into contact with the appropriate conveying elements. For example, the printing medium can lie midway on an electrostatic conveyor belt and be conveyed thereby while one edge or even both edges of the printing medium make no contact.
This freedom of contact of the edges can, for example, be necessary when microwave fuser mechanisms are used, as is proposed in DE 101 45 005 A1. In such case, for example, toner can initially be fused on the edges of the printing medium by microwaves. Because contacts made by the printing medium directly downstream of the microwave applicators can lead to smeared print images, it is desirable that the printing medium be conveyed in such a way that no contact is made with the edges. To achieve this purpose, the use of an electrostatic conveyor belt for conveying the printing medium is preferred, whereby the conveyor belt is set up such that the middle section of printing medium lies on the conveyor belt.
If the printing medium is conveyed such that the edges do not make contact, undesirable movements of the edges can occur. The edge can begin to flutter or become bent in an undesirable way; it can, in particular, hang down or roll up, or the like.
The undesirable movements can cause reductions in print quality. The layer of toner can be adversely affected or, inside a lithographic or ink jet printing machine, ink that has not yet dried can run. If the path of travel runs through another mechanism, the movements of the edges of the printing medium can result in the medium making contact with or bumping into feed-in slots that are present. This can damage the printing medium, or cause a paper jam.